This invention relates to the preparation of 1,3-propanediol. In one aspect, the invention relates to a cobalt-catalyzed process for manufacturing 1,3-propanediol in high yields without the use of a phosphine ligand for the cobalt catalyst.
1,3-propanediol (PDO) is an intermediate in the production of polyesters for fibers and films. It is known to prepare PDO in a two-step process involving (1) the cobalt-catalyzed hydroformylation (reaction with synthesis gas, CO/H.sub.2) of ethylene oxide to intermediate 3-hydroxypropanal (HPA) and (2) hydrogenation of the HPA to PDO. The initial hydroformylation step is carried out at temperatures greater than 100.degree. C. and at high synthesis gas pressure to achieve practical reaction rates. The resulting product mixture is, however, rather unselective for HPA.
In an alternate hydroformylation method, the cobalt catalyst is used in combination with a phosphine ligand to prepare HPA with greater selectivity and at lower temperature and pressure. However, the use of a phosphine ligand adds to the cost of the catalyst and increases the complexity of catalyst recycle.
It would be desirable to prepare HPA in a low-temperature, selective process which did not require the use of a phosphine ligand with the cobalt catalyst.
It is therefore an object of the invention to provide an economic process for the preparation of 1,3-propanediol which does not require the use of a phosphine-ligated catalyst. It is a further object of the invention to provide a cobalt-catalyzed process for the preparation of 1,3-propanediol in which the majority of the cobalt catalyst can be conveniently recycled.